A. Field of the Invention
The present invention relates to a compact wide-angle zoom lens system, and, more particularly, to a compact wide-angle zoom lens system comprising two lens groups and having a zoom ratio of about 2.0 times.
B. Description of the Related Art
Automatic compact cameras have been recently provided with zoom lenses and panorama structures. As a result, users require these cameras to be compact and to have a wide viewing angle. In order to reduce a camera's size, however, the camera's optical system must first be reduced.
Generally, zoom lens systems for compact cameras can be divided into two types: those having two lens groups and those having three lens groups. The two lens group type is compact and light, but does not provide a high magnification. The three lens group type, on the other hand, provides a high magnification, but is large and heavy.
Zoom lens systems having two lens groups are disclosed in tile U.S. Pat. No. 4,936,661 and Japanese Publication Nos. Hei 5-224122, Hei 5-82696, and Hei 5-289294. The zoom lens system of U.S. Pat. No. 4,936,661 has a very short back focal length, making the size of the rear lens group large in order to obtain a marginal illumination. As a consequence, it is very difficult to reduce the lens system's size.
The zoom lens system of Hei 5-224122 does not have a wide angle. It, therefore, has a large telephoto ratio at a telephoto position which also makes it difficult to obtain a compact camera. The zoom lens system of Hei 5-82696 suffers from the fact that it has a poor zoom ratio of less than 1.9 times. The zoom lens system of Hei 5-289294 has a large telephoto ratio at a telephoto position, but has a large number of lenses making it expensive to manufacture.